Judith Herrin is one of the most distinguished historians of Byzantium writing today, and it is a joy to see the publication of her essays in two volumes: the collection being reviewed here and the collection in Unrivalled Influence: Women and Empire in Byzantium (Princeton, N.J.: Princeton University Press, 2013). As a historian of Byzantium, I was especially intrigued by the autobiographical introduction and by the brief introductions to each essay. One of the early students in what has become the famed Byzantine and Modern Greek Studies program at Birmingham University, Herrin knows a great deal about the history of the field, and her introductions provide a kind of outline of its development.

For the readers of Church History , the chapters of interest are likely to be 11, 12, 13, 14, and 16; the rest of this review will therefore be devoted to those. One crucial context for these articles is Herrin's ground-breaking and comprehensive study of early medieval Christian societies, The Formation of Christendom (Princeton, N.J.: Princeton University Press, 1987). Historians of late antiquity, of early medieval western Europe, and of early medieval Byzantium know that this work has become fundamental to our understanding. Herrin argued that we cannot understand any one of the societies of early medieval Europe and western Asia without understanding its interactions with the others, and her thorough investigation of those relationships convinced scholars in several fields. Chapter 11 is one of several articles that elaborate upon themes treated more briefly in Formation : "Constantinople, Rome, and the Franks in the Seventh and Eighth Centuries" explores the decades before and after the famous moment when Pope Stephen II (752-757) turned to the Franks for protection. The conclusions Herrin reaches about the impact of this turn on the history of the churches have become basic tenets of early medieval history. For example, she argues that every step of the process by which the popes turn away from the emperor in Constantinople and toward the kings of the Franks must be understood as a triangular process. In other words, this is not about "East" and "West"; it is about popes, Franks, and Byzantines. On some subjects, the popes and the Constantinopolitans agree; on others, the popes ally with the Franks; the Byzantine iconoclast emperors try to go around the pope to make an alliance with the Franks. This idea of a triangle of relationships has become so basic to early medieval history that it is hard to remember how we thought of these things before Herrin's work. Nevertheless, it is her work that moved us from a dualistic model of East versus West to a more subtle understanding of early medieval Weltpolitik , and this article is an excellent short introduction to the basic idea.

Chapter 12, "The Pentarchy: Theory and Reality in the Ninth Century," is a lucid account of the development of ideas about where the ultimate authority in the church lies. …